Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientiﬁc data. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our ﬁndings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientiﬁcally sound conservation and policy intervention is needed to reduce this impact.

A new peer-reviewed study published today and authored by scientists from two of the world’s leading science and wildlife organizations – the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service (FWS) – has found that bird and mammal mortality caused by outdoor cats is much higher than has been widely reported, with annual bird mortality now estimated to be 1.4 to 3.7 billion and mammal mortality likely 6.9 – 20.7 billion individuals.

The study, which offers the most comprehensive analysis of information on the issue of outdoor cat predation, was published in the online research journal Nature Communications and is based on a review of 90 previous studies. The study was authored by Dr. Peter Marra and Scott Loss, research scientists at the Smithsonian Conservation Biology Institute and by Tom Will from the U.S. Fish and Wildlife Service’s Division of Migratory Birds.

According to Dr. George Fenwick, President of American Bird Conservancy, one of the leading bird conservation organizations in the U.S. and a group that has called for action on this issue for many years, "This study, which employed scientifically rigorous standards for data inclusion, demonstrates that the issue of cat predation on birds and mammals is an even bigger environmental and ecological threat than we thought. No estimates of any other anthropogenic [human-caused] mortality source approach the bird mortality this study calculated for cat predation.”

“To maintain the integrity of our ecosystems, we have to conserve the animals that play integral roles in those ecosystems. Every time we lose another bird species or suppress their population numbers, we’re altering the very ecosystems that we depend on as humans. This issue clearly needs immediate conservation attention,” he said further.

“The very high credibility of this study should finally put to rest the misguided notions that outdoor cats represent some harmless, new component to the natural environment. The carnage that outdoor cats inflict is staggering and can no longer be ignored or dismissed. This is a wake-up call for cat owners and communities to get serious about this problem before even more ecological damage occurs,” Fenwick said.

The study’s estimate of bird mortality far exceeds any previously estimated U.S. figure for cats. In fact, this magnitude of mortality may exceed all other direct sources of anthropogenic bird and mammal mortality combined. Other bird mortality sources would include collisions with windows, buildings, communication towers, vehicles, and pesticide poisoning.

The study estimated that the median number of birds killed by cats annually is 2.4 billion and the median number of mammals killed is 12.3 billion. About 69 percent of the bird mortality from cat predation and 89 percent of the mammal mortality was from un-owned cats. Un-owned cats are defined to include farm/barn cats, strays that are fed but not granted access to human habitations, cats in subsidized colonies, and cats that are completely feral.

Free-ranging cats on islands have caused or contributed to 33 (14 percent) of the modern bird, mammal, and reptile extinctions recorded by the International Union for Conservation of Nature Red List of threatened animals and plant species.

Native species make up the majority of the birds preyed upon by cats. On average, only 33 percent of bird prey items identified to species were non-native species in 10 studies. Studies of mammals in suburban and rural areas found that 75–100 percent of mammalian prey were native mice, shrews, voles, squirrels, and rabbits, all of which serve as food sources for birds of prey such as hawks, owls, and eagles.

The study charges that, “Despite these harmful effects, policies for management of free-ranging cat populations and regulation of pet ownership behaviors are dictated by animal welfare issues rather than ecological impacts. Projects to manage free-ranging cats, such as Trap-Neuter-Return (TNR) colonies, are potentially harmful to wildlife populations, but are implemented across the United States without widespread public knowledge, consideration of scientific evidence, or the environmental review processes typically required for actions with harmful environmental consequences.”

The Impact of free-ranging Domestic Cats on Wildlife of the United States

Wednesday, January 30, 2013

The emergence of Cetacea in the Paleogene represents one of the most profound macroevolutionary transitions within Mammalia. The move from a terrestrial habitat to a committed aquatic lifestyle engendered wholesale changes in anatomy, physiology, and behavior. The results of this remarkable transformation are extant whales that include the largest, biggest brained, fastest swimming, loudest, deepest diving mammals, some of which can detect prey with a sophisticated echolocation system (Odontoceti – toothed whales), and others that batch feed using racks of baleen (Mysticeti – baleen whales). A broad-scale reconstruction of the evolutionary remodeling that culminated in extant cetaceans has not yet been based on integration of genomic and paleontological information. Here, we first place Cetacea relative to extant mammalian diversity, and assess the distribution of support among molecular datasets for relationships within Artiodactyla (even-toed ungulates, including Cetacea). We then merge trees derived from three large concatenations of molecular and fossil data to yield a composite hypothesis that encompasses many critical events in the evolutionary history of Cetacea. By combining diverse evidence, we infer a phylogenetic blueprint that outlines the stepwise evolutionary development of modern whales. This hypothesis represents a starting point for more detailed, comprehensive phylogenetic reconstructions in the future, and also highlights the synergistic interaction between modern (genomic) and traditional (morphological + paleontological) approaches that ultimately must be exploited to provide a rich understanding of evolutionary history across the entire tree of Life.

Highlights:

► The origin of Cetacea (whales) represents a key macroevolutionary transition within Mammalia. ► We assess the distribution of support among molecular datasets for Artiodactyla relationships. ► Three supermatrices of molecular and fossil data yield a composite phylogenetic hypothesis. ► We infer a phylogenetic blueprint that outlines the stepwise evolution of modern whales.

The Oxford Clay Formation of England has yielded numerous sympatric species of metriorhynchid crocodylomorphs, although disagreement has persisted regarding the number of valid species. For over 140 years teeth reminiscent of the genus Dakosaurus have been known from the Oxford Clay Formation but these have never been properly described and their taxonomy and systematic affinity remain contentious. Furthermore, an enigmatic mandible and associated postcranial skeleton discovered by Alfred Leeds in the Fletton brick pits near Peterborough also remains undescribed. We show that this specimen, and several isolated teeth, represents the oldest known remains of a large-bodied predatory metriorhynchid. This material is described herein and referred to Tyrannoneustes lythrodectikos gen. et sp. nov. This species has a unique occlusal pattern: the dentition was arranged so that the posterior maxillodentary teeth interlock in the same plane and occlude mesiodistally. It is the first described crocodylomorph with microscopic denticles that are not contiguous along the carinae (forming short series of up to 10 denticles) and do not noticeably alter the height of the keel. Additionally, the dorsally expanded and curved posterior region of the mandible ventrally displaced the dentary tooth row relative to the jaw joint facilitating the enlargement of the dentition and increasing optimum gape. Therefore, Tyrannoneustes would have been a large-bodied marine predator that was well-suited to feed on larger prey than other contemporaneous metriorhynchids. A new phylogenetic analysis finds Tyrannoneustes to be the sister taxon to the subclade Geosaurini. An isolated tooth, humerus, and well-preserved mandible suggest a second species of metriorhynchid super-predator may also have lived in the Oxford Clay sea. Finally, we revise the diagnoses and descriptions of the other Oxford Clay metriorhynchid species, providing a guide for differentiating the many contemporaneous taxa from this exceptional fossil assemblage.

Fossil remains in museum found to be 165 million year old marine super-predator

—Researchers examining a fossil specimen discovered in a museum storage bin have found it to be the remains of a super-predator that lived during the Jurassic Period, around 165 million years ago. They describe the specimen, named Tyrannoneustes lythrodectikos, as looking like a cross between a modern dolphin and a shark or crocodile.

Tyrannoneustes lythrodectikos, meaning "tyrant swimmer that bites" in Latin, was found in 1919 in a clay pit near the British town of Peterborough (the Oxford Clay Formation) by an amateur bone collector. Since that time it has resided, hidden away in Glasgow's Hunterian museum. The skeletal remains include a jawbone with serrated teeth that the researchers, from the University of Edinburgh describe as an indication that the creature was a super-predator one that preys on animals that are as big as it is, or even bigger.

The research team, led by Mark Young, says the time period during which the tyrant swimmer lived would have had it swimming in the shallow seas that covered much of Europe and England along with other large marine predators. At the time, the area consisted of a chain of islands. They believe T. lythrodectikos would have been a very strong swimmer it had a fluked tail and forelimbs that resembled flippers and was able to open its mouth very wide to allow for biting into large prey. It would have been both a formidable hunter and an elusive target for other larger marine animals. But if caught, would not have been difficult to eat as it lacked the bony armor of other species of the time.

The Middle Jurassic period, as has been glamorized by Hollywood, was a time during which many very large animals existed, many of them predatory. Their existence, scientists say, indicates a time when there was a very healthy food chain.

The team adds that the species is the oldest known super-predator, and notes that little research had been done on the skeletal remains over the near century since it was brought to the museum. They also report that no stomach contents were found, thus they can't say for sure what the animal ate.

Young, M. T.; De Andrade, M. B.; Brusatte, S. L.; Sakamoto, M.; Liston, J. 2013. The oldest known metriorhynchid super-predator: A new genus and species from the Middle Jurassic of England, with implications for serration and mandibular evolution in predacious clades. Journal of Systematic Palaeontology: 1. doi:10.1080/14772019.2012.704948

Many fossil animals bear traits such as crests or horns that probably functioned as sexually selected signals or weapons. Interpretations of these structures as functioning in mate choice or intrasexual contests are often controversial, with interpretations based on biomechanics or physiology being favoured by many. Although testing hypotheses based on sexual selection can be difficult, especially given that there is no single, reliable means of recognising sexual selection, we argue that it is not impossible; indeed, there are now several cases where sexual selection is strongly supported. In other cases, a careful study of features such as sexual dimorphism, ontogeny, and allometry, coupled with testing of alternative hypotheses, will be necessary to distinguish between possible explanations for exaggerated features.

Sex-related features of Darwinopterus. The male (right) has a large head crest, but this is absent in the female (left). The coloring of the animals is very uncertain, but the dramatic differences in crest structure are shown by the new fossil evidence reported in a study by Lu et al. [Art: Mark Witton]

The term “sexual selection” refers to the evolutionary pressures that relate to a species’ ability to repel rivals, meet mates and pass on genes. One can observe these processes happening in living animals but how do paleontologists know that sexual selection operated in fossil ones?

Paleontologists have thought it challenging, even impossible, to recognize sexual selection in extinct animals. Many fossil animals have elaborate crests, horns, frills and other structures that look like they were used in sexual display but it can be difficult to distinguish these structures from those that might play a role in feeding behavior, escaping predators, controlling body temperature and so on.

However in the new study, the paleontologists argue that clues in the fossil record can indeed be used to infer sexual selection. “We see much evidence from the fossil record suggesting that sexual selection played a major role in the evolution of many extinct groups,” said study co-author Dr Darren Naish of the University of Southampton.

“Using observations of modern animal behavior we can draw analogies with extinct animals and infer how certain features improve success during courtship and breeding.”

Modern examples of sexual selection, where species have evolved certain behaviors or ornamentation that repel rivals and attract members of the opposite sex, include the male peacock’s display of feathers, and the male moose’s antlers for use in clashes during mating season.

“The fossil record holds many clues that point to the existence of sexual selection in extinct species, for example weaponry for fighting, bone fractures from duels, and ornamentation for display, such as fan-shaped crests on dinosaurs. Distinct differences between males and females of a species, called ‘sexual dimorphism’, can also suggest the presence of sexual selection, and features observed in sexually mature adults, where absent from the young, indicate that their purpose might be linked to reproduction.”

“Some scientists argue that many of the elaborate features on dinosaurs were not sexually selected at all,” Dr Naish said.

“But as observations show that sexual selection is the most common process shaping evolutionary traits in modern animals, there is every reason to assume that things were exactly the same in the distant geological past.”

Specimen ZMNH M8802, a female individual of Darwinopterus, from the Tiaojishan Formation (upper Middle-lower Upper Jurassic) of Liaoning Province, China.
(A) Partially prepared, exposing the skull, neck and left forelimb, but with the egg still almost completely encased in the rock. (B) Fully prepared with the entire skeleton and egg now completely exposed. [photo: Junchang Lü̈]

Researchers in China have discovered an adult pterosaur fossil preserved together with one of its eggs. The pterosaurs, also known as pterodactyls, were winged reptiles that lived during the Jurassic period, and the presence of an egg with one of their fossils indicates that this pterosaur was definitely female. Now, researchers report details of the egg and compare the males and females of this pterosaur species, Darwinopterus.

Junchang Lü from the Chinese Academy of Geological Sciences in Beijing, along with colleagues in China and the United Kingdom, excavated the Darwinopterus fossil from sedimentary rocks in China’s Liaoning Province, and they estimate its age to be approximately 160 million years old. The nearly complete skeleton is described in the 21 January issue of the journal Science.

The discovery helped researchers learn more about male Darwinopterus by comparing previously discovered fossils with the new female fossil. The new find confirms that males had relatively small pelvises and large cranial crests, or extensions of bone on the top of their skulls. The females, on the other hand, had much larger pelvises but no cranial crests, according to the researchers.

“Darwinopterus females had no crest at all,” said Lü. “In the males, it was long and low-extending—from just above the nasal opening to the apex of the skull, just behind the orbit... Pterosaur males had a huge array of different kinds of head crests, varying from small keels on the jaws to huge sail-like structures that might reach as much as five times the height of the skull.”

Details of the fossilized egg imply that the pterosaur’s reproductive strategies were not like those of birds, as most researchers had previously suspected, but more like those of crocodiles or other reptiles. Lü and the team of researchers say that the egg is relatively small compared to the pterosaur’s body and that it was likely soft and covered in a parchment-like shell.

They note that, today, birds the size of a pterosaur would likely produce eggs nearly three times the size of this fossilized egg, since rigid bird shells must contain all the resources needed to sustain the developing embryo inside. Instead, the soft, fossilized shell suggests that Darwinopterus females buried their eggs like reptiles, paying little attention to them as they soaked up nutrients from the ground.

“The eggs could absorb water from their environment, and they likely increased in size and mass during this period—possibly doubling the original mass by the time they hatched,” said Lü. “This also means that the adult did not have to invest so much water in the egg, which could have been quite advantageous: Less material investment in the egg and less mass to carry around while the egg was being produced in the female’s body.”

And how did this one particular pterosaur meet its fate in order to become such a beautifully preserved fossil? The researchers have a few ideas about that too.

“It seems that the left forearm is broken, so we suspect that Mrs. T—that’s our nickname for this specimen—had an accident, perhaps in a storm or possibly as a result of a volcanic eruption, which were very common in this part of China at the time,” said Lü. “She ended up in the water—in a lake—and then sank to the bottom, drowning on the way. The egg was expelled from the body as Mrs. T began to decay.”

Average earth temperatures rose 0.6 °C over the last century, according to the latest Intergovernmental Panel on Climate Change. But that increase pales in comparison to the 1.4–5.8 °C expected increase over this century. As temperatures climb, climate models predict that high-latitude, high-altitude regions like Yellowstone National Park will experience shorter winters and earlier snow melts. How these environmental shifts will impact species and ecosystems remains to be seen.

The effects of climate change are already evident at the species level, with disruptions in range, reproductive success, and seasonal phenomena like migration, and the decoupling of evolutionarily paired events like new births and food availability. Both experimental and data-driven modeling studies predict that climate change may well precipitate shifts in the structure of ecosystems as well.

In a new study, Christopher Wilmers and Wayne Getz investigated the effects of climate change on ecosystem dynamics by studying a keystone species in Yellowstone, the gray wolf (Canis lupus). Gray wolves inhabited most of North America until US extirpation campaigns nearly eradicated them by the 1930s. In 1995, the US Fish and Wildlife Service reintroduced the persecuted predator into Yellowstone.

crab from Christmas Island has been named for Art Garfunkel, in tribute to his song “Bright eyes” and one can certainly see why!

The paper by Peter Davie and Peter Ng is published in the latest issue of Zootaxa and revises the Chiromantes obtusifron complex. From one wide-spread Indo-West Pacific species, there are now five species with discrete distributions. The realChiromantes obitusifrons is now known to be endemic to Hawaii Islands, while C. garfunkel sp. nov. is endemic to Christmas Island, Indian Ocean. Chiromantes silus sp. nov. is endemic to Guam. Chiromantes leptomerus sp. nov. is known from Taiwan and the Ryukyu Islands, southern Japan while Chiromantes eurymerus sp. nov. is endemic to Taiwan.

The identity of Chiromantes obtusifrons (Dana, 1851), previously considered widespread in the tropical West Pacific region to the eastern Indian Ocean, is revised and found to be a species-complex. Chiromantes obtusifrons is now considered endemic to the Hawaiian Is., and four new species are described from Guam, Taiwan and Christmas Island. Two species live sympatrically in Taiwan. Species separation is based on carapace and frontal shape and granulation, leg proportions, abdominal somite proportions, and distinctive live colouration.

The identity of Chiromantes obtusifrons (Dana, 1851), previously considered widespread in the tropical West Pacific region to the eastern Indian Ocean, is revised and found to be a species-complex. Chiromantes obtusifrons is now considered endemic to the Hawaiian Is., and four new species are described from Guam, Taiwan and Christmas Island. Two species live sympatrically in Taiwan. Species separation is based on carapace and frontal shape and granulation, leg proportions, abdominal somite proportions, and distinctive live colouration.

The realChiromantes obitusifrons is now known to be endemic to Hawaii Islands, while C. garfunkel sp. nov. is endemic to Christmas Island, Indian Ocean. Chiromantes silus sp. nov. is endemic to Guam. Chiromantes leptomerus sp. nov. is known from Taiwan and the Ryukyu Islands, southern Japan while Chiromantes eurymerus sp. nov. is endemic to Taiwan.

Sunday, January 27, 2013

Figure 3 A series of six elasmotheres species from the Middle Miocene to the Late Pleistocene. They display an increase in skull size and development from a nasal horn to a frontal horn.
These skulls are reconstructed based on
AMNH 26531 (Tunggur in Inner Mongolia, Middle Miocene) for Hispanotherium tungurense,
HMV 0979 (Houshan in Guanghe, Gansu, Late Miocene) for Iranotherium morgani,
HMV 1411 (Guonigou in Dongxiang, Gansu, Late Miocene) for Parelasmotherium linxiaense,
HMV 1449 (Guonigou in Dongxiang, Gansu, Late Miocene) for Ningxiatherium euryrhinus,
V 18539 (Huaigou in Guanghe, Gansu, Late Miocene) for Sinotherium lagrelii, and
NHM 12429 (Sarepta in Russia, Late Pleistocene) for Elasmotherium sibiricum.

Although the modern Indian and Javan rhinos have a single horn on their noses, the extinct one-horned rhino Elasmotherium was a source for the legendary unicorn, because the latter had a very long horn on its forehead and lived with the prehistoric human beings who drew its images on cave paintings. Elasmothere rhinos first appeared in South Asia in the Early Miocene, but the origin of Elasmotherium has been unclear. All other elasmotheres have a weak or strong nasal horn, whereas Elasmotherium seems to lose the nasal horn of its ancestors and to get a huge frontal horn apparently abruptly. Here we report the first discovered skull of Sinotherium lagrelii from the Late Miocene red clays in the Linxia Basin, northwestern China. This skull has an enormous nasofrontal horn boss shifted posteriorly and a smaller frontal horn boss, which are connected to each other, indicating an intermediate stage for the single frontal horn of Elasmotherium. Morphological and phylogenetic analyses confirm that Sinotherium is a transitional taxon between Elasmotherium and other elasmotheres, positioned near the root of the giant unicorn clade and originated in a subarid steppe. The posteriorly shifted nasal horn has a more substantial support and the arched structure of the nasofrontal area is an adaptation for a huge horn.

The Linxia Basin is located on the triple-junction of the northeastern Tibetan Plateau, western Qinling Mountains and the Loess Plateau. The basin is filled with 700−2000 m of late Cenozoic deposits, mainly red in color and dominated by lacustrine siltstones and mudstones, and the Linxia sequence represents the most complete and successive late Cenozoic section in China. The localities in the Linxia Basin are notable for abundant, relatively complete, well-preserved, and sometimes partially articulated bones of large mammals, which often occur in dense concentrations. Many new species of the Late Oligocene Dzungariotherium fauna, the Middle Miocene Platybelodon fauna, the Late Miocene Hipparion fauna, and the Early Pleistocene Equus fauna have been described from the Linxia Basin since 2000, including rodents, lagomorphs, primates, carnivores, proboscideans, perissodactyls and artiodactyls.

Among these mammalian fossils, several hundred skulls of the late Cenozoic rhinoceroses are known from the Linxia Basin. In addition, more abundant limb bones and isolated teeth of rhinoceroses are found in this basin, especially from the Late Miocene red clay deposits. Rhinoceroses were over 70% in diversity during the Late Oligocene, and they were dominant in population during the Late Miocene. In the Middle Miocene and Early Pleistocene faunas, rhinoceroses were important members.

The extinct giant stork Leptoptilos robustus would have dwarfed the "hobbit" Homo floresiensis living on the Indonesian Island of Flores. (artist's impression)

Art: Inge van Noortwijk

Leptoptilos robustus Meijer & Due 2010

Abstract

Fossils of the genus Leptoptilos from the Pleistocene of Liang Bua, Flores, Indonesia, belong to a new species of giant marabou stork, Leptoptilos robustus sp. nov. This giant bird, estimated at 1.80 m in length, was similar in dimensions to extant Leptoptilos dubius, except for the tibiotarsus. The thick cortical bone wall of the tibiotarsus and the estimated weight of 16 kg imply a reduced flight capability. Osteological and biometric characters suggest that L. robustus is most closely related to L. dubius. An evolutionary lineage is proposed in which a volant L. dubius-like ancestor in the Middle Pleistocene evolved into the Late Pleistocene L. robustus on Flores, with a concomitant reduction of the ability to fly and an increase in body size. The large body size and terrestrial lifestyle of L. robustus are responses to an unbalanced, insular environment with abundant prey items and a lack of mammalian carnivores, and emphasize the extraordinary nature of the Homo floresiensis fauna.

DNA barcoding of non-avian reptiles based on the cytochrome oxidase subunit I (COI) gene is still in a very early stage, mainly due to technical problems. Using a newly developed set of reptile-specific primers for COI we present the first comprehensive study targeting the entire reptile fauna of the fourth-largest island in the world, the biodiversity hotspot of Madagascar.

Methodology/Principal Findings

Representatives of the majority of Madagascan non-avian reptile species (including Squamata and Testudines) were sampled and successfully DNA barcoded. The new primer pair achieved a constantly high success rate (72.7–100%) for most squamates. More than 250 species of reptiles (out of the 393 described ones; representing around 64% of the known diversity of species) were barcoded. The average interspecific genetic distance within families ranged from a low of 13.4% in the Boidae to a high of 29.8% in the Gekkonidae. Using the average genetic divergence between sister species as a threshold, 41–48 new candidate (undescribed) species were identified. Simulations were used to evaluate the performance of DNA barcoding as a function of completeness of taxon sampling and fragment length. Compared with available multi-gene phylogenies, DNA barcoding correctly assigned most samples to species, genus and family with high confidence and the analysis of fewer taxa resulted in an increased number of well supported lineages. Shorter marker-lengths generally decreased the number of well supported nodes, but even mini-barcodes of 100 bp correctly assigned many samples to genus and family.

Conclusions/Significance

The new protocols might help to promote DNA barcoding of reptiles and the established library of reference DNA barcodes will facilitate the molecular identification of Madagascan reptiles. Our results might be useful to easily recognize undescribed diversity (i.e. novel taxa), to resolve taxonomic problems, and to monitor the international pet trade without specialized expert knowledge.

Friday, January 25, 2013

A new fossil spider from the Triassic (Norian) Dolomia di Forni Formation of Friuli, Italy, is described as Friularachne rigoi gen. et sp. nov. This find brings the number of known Triassic spider species to four. The specimen is an adult male, and consideration of various features, including enlarged, porrect chelicerae, subequal leg length, and presence of a dorsal scutum, point to its identity as a possible member of the

mygalomorph superfamily Atypoidea. If correct, this would extend the geological record of the superfamily some 98–115 Ma from the late Early Cretaceous (?Albian, c. 100–112 Ma) to the late middle–early late Norian (c. 210–215 Ma).

Wednesday, January 23, 2013

- Penguins are weird birds in that they cannot fly and are instead proficient swimmers and divers.

- Evolutionary biologists have long wondered how penguins evolved their peculiar traits and how some of their kind conquered the bitterly cold Antarctic.

- Recent fossil discoveries have enabled researchers to piece together the penguins' evolutionary past, revealing that some of the traits that fortify them against the cold evolved under warm conditions.

- Although penguins have triumphed over 60 million years of climate change, current warming conditions may outpace their ability to adapt.

Hundreds of specimens of the beaked bird Confuciusornis sanctus have been recovered from Early Cretaceous lake deposits of northeastern China. These birds show remarkable variation in size and plumage, with some displaying two long, central ornamental rectrices (tail feathers) and others lacking them altogether. Although, traditionally specimens with ornamental rectrices were interpreted as males and those without them as females, this supposed sexual dimorphism has remained unconfirmed. Here we report on the discovery of medullary bone, a tissue unique to reproductively active female birds, in a specimen of C. sanctus (DNHM-D1874) lacking these feathers. Our discovery constitutes the first case of gender identification in a Mesozoic bird, and it provides undisputed evidence that individuals of C. sanctus without ornamental rectrices are females. By permitting gender identification in C. sanctus, our results provide insight into the onset of sexual maturity and attainment of adult body size of this and other early birds.

In a paper published in Nature Communications on January 22, 2013, a team of paleontologists including Dr. Luis Chiappe, Director of the Natural History Museum of Los Angeles County's (NHM) Dinosaur Institute, has discovered a way to determine the sex of a prehistoric bird species.

Confuciusornis sanctus, a 125-million-year-old Mesozoic bird, had remarkable differences in plumage -- some had long, almost body length ornamental tail feathers, others had none -- features that have been interpreted as the earliest example of avian courtship. However, the idea that male Confuciusornis birds had ornamental plumage, and females did not, has not been proven until now. Chiappe and the team studied hundreds of Confuciusornis fossils unearthed from rocks deposited at the bottom of ancient lakes in what is today northeastern China and found undisputed evidence of the gender difference: medullary bone.

Chiappe conducted the study with Anusuya Chinsamy of the Department of Biological Sciences, University of Cape Town, South Africa; Jesús Marugán-Lobón of Madrid's Universidad Autonóma, Cantoblanco; Gao Chunling and Zhang Fengjiao of the Dalian Natural History Museum in China.

"Our discovery provides the first case of sex identification in an ancient bird, an animal closely related to dinosaurs, such as the famous Velociraptor," said Chiappe. "When people visit dinosaur exhibits, they often want to know if the skeletons are male or female. We have nicknames like Thomas and Sue, but of all the thousands of skeletons of dinosaurs or early birds found around the world, only the sex of a few has been determined."

According to Chinsamy, the bone histologist on the team, "Just like modern hens, female Confuciusornis birds that lived 125 million years ago deposited this special bone inside their long bones, and then used it to make the calcium-rich eggshells." Finding such tissue -- present during a short period of time in reproductively active females -- in a specimen that lacked long feathers proved that those birds without ornamental plumage are females.

"This now permits us to assess gender differences in growth and development of this Mesozoic bird," she said.

But while this discovery offers evidence that both early and modern female avian species were essentially using the same physiological strategy to reproduce, it also spotlights an important difference in when they sexually matured.

"In human terms, knowing the sex of these specimens sheds light on when these early birds begin puberty," said Chiappe, "Now we know that early birds began reproducing way before they were full grown, a pattern that contrasts with what we know of living birds, which typically begin reproducing after they reach full body size." In that way, ancient birds produced offspring like dinosaurs, which also began to reproduce before they were fully grown.

The specimens, housed at the Dalian Natural History Museum in northeastern China, had been excavated from rocks formed at the bottom of ancient lakes in a forested environment surrounded by volcanoes. Ancient catastrophes, presumably related to volcanic eruptions, killed large numbers of birds and other animals, whose bodies were buried deep in the lake mud that helped minimize decay and preserving the organs, skeletons, and plumage. "This discovery is part of the big picture of understanding the early evolution of birds,'' Chiappe said, "and how living birds became what they are."

Feathered theropods were diverse in the Early Cretaceous Jehol Group of western Liaoning Province, China. Recently, anatomically distinct feathered taxa have been discovered in the older Middle-Late Jurassic Tiaojishan Formation in the same region. Phylogenetic hypotheses including these specimens have challenged the pivotal position of Archaeopteryx in bird phylogeny. Here we report a basal troodontid from the Tiaojishan Formation that resembles Anchiornis, also from Jianchang County (regarded as sister-taxa). The feathers of Eosinopteryx are less extensive on the limbs and tail than Anchiornis and other deinonychosaurians. With reduced plumage and short uncurved pedal claws, Eosinopteryx would have been able to run unimpeded (with large foot remiges cursorial locomotion was likely problematic for Anchiornis). Eosinopteryx increases the known diversity of small-bodied dinosaurs in the Jurassic, shows that taxa with similar body plans could occupy different niches in the same ecosystem and suggests a more complex picture for the origin of flight.

Paleontologists have discovered in Liaoning remains small dinosaur with unusually short feathers, lived in China 156 million years ago, which suggests the diversity of species of dinosaurs have feathers in the Jurassic period, according to a paper published in the journal Nature Communications.